The gas circuit breaker is used in an electric power system for interrupting a fault current occurring due to interphase short circuit, ground fault or the like. Heretofore, the puffer type gas circuit breakers have been used widely. In this puffer type gas circuit breaker, a high-pressure gas flow is generated by mechanically compressing an arc-extinguishing gas by means of a movable puffer cylinder directly connected to a movable arc contact. The resultant gas flow is blown onto an arc generated between the movable arc contact and a stationary arc contact so that an electric current is interrupted.
The current interruption performance of the gas circuit breaker is dependent on pressure buildup in a puffer chamber. In this connection, a heat puffer combination type gas circuit breaker adapted for pressure buildup by active use of the heat energy of arc as well as for hitherto known pressure buildup based on mechanical compression is also used extensively. The heat puffer combination type gas circuit breaker utilizes the heat energy of arc for generating a pressure for applying a blast of arc-extinguishing gas. As compared with the conventional device based on mechanical compression, this type of gas circuit breaker can reduce operational energy required for interruption operation.
On the other hand, the heat energy of arc is proportional to the fault current. In the interruption of a large current, the arc has such large heat energy as to generate a high pressure. In the interruption of a small to medium current, however, the arc heat provides a small pressure buildup. Therefore, the pressure generated by mechanical compression is used for blowing the arc-extinguishing gas onto the arc so as to interrupt the electric current.
Patent Literature 1 discloses a puffer type gas circuit breaker which includes: a heat gas chamber formed in the puffer chamber; a separator substantially shaped like a cylinder and disposed between an insulation nozzle and a movable arcing contact; a first release path for guiding an insulation gas from the heat gas chamber to a vicinity of a through hole (arc space); and a second release path for guiding the insulation gas from the puffer chamber to the vicinity of the through hole.